CodeGenerator.java

import java.io.*;
import java.util.LinkedList;

public class CodeGenerator {

  LinkedList<Instruction> instructions = new LinkedList<Instruction>();

  int label = 0;

  public void emit(OpCode opCode) { instructions.add(new Instruction(opCode)); }

  public void emit(OpCode opCode, int operand) {
    instructions.add(new Instruction(opCode, operand));
  }

  public void emitLabel(int operand) { emit(OpCode.label, operand); }

  public int newLabel() { return label++; }

  public void toJasmin() throws IOException {
    PrintWriter out = new PrintWriter(new FileWriter("Output.j"));
    String temp = "";
    temp = temp + header;
    while (instructions.size() > 0) {
      Instruction tmp = instructions.remove();
      temp = temp + tmp.toJasmin();
    }
    temp = temp + footer;
    out.println(temp);
    out.flush();
    out.close();
  }

  private static final String header =
      ".class public Output \n"
      + ".super java/lang/Object\n"
      + "\n"
      + ".method public <init>()V\n"
      + " aload_0\n"
      + " invokenonvirtual java/lang/Object/<init>()V\n"
      + " return\n"
      + ".end method\n"
      + "\n"
      + ".method public static print(I)V\n"
      + " .limit stack 2\n"
      + " getstatic java/lang/System/out Ljava/io/PrintStream;\n"
      + " iload_0 \n"
      + " invokestatic java/lang/Integer/toString(I)Ljava/lang/String;\n"
      + " invokevirtual java/io/PrintStream/println(Ljava/lang/String;)V\n"
      + " return\n"
      + ".end method\n"
      + "\n"
      + ".method public static read()I\n"
      + " .limit stack 3\n"
      + " new java/util/Scanner\n"
      + " dup\n"
      + " getstatic java/lang/System/in Ljava/io/InputStream;\n"
      + " invokespecial java/util/Scanner/<init>(Ljava/io/InputStream;)V\n"
      + " invokevirtual java/util/Scanner/next()Ljava/lang/String;\n"
      + " invokestatic java/lang/Integer.parseInt(Ljava/lang/String;)I\n"
      + " ireturn\n"
      + ".end method\n"
      + "\n"
      + ".method public static run()V\n"
      + " .limit stack 1024\n"
      + " .limit locals 256\n";

  private static final String footer =
      " return\n"
      + ".end method\n"
      + "\n"
      + ".method public static main([Ljava/lang/String;)V\n"
      + " invokestatic Output/run()V\n"
      + " return\n"
      + ".end method\n";
}